Impedance Spectroscopy for Determination of Total Dissolved Solids in Aqueous Solutions of Sodium Chloride and Magnesium Sulphate

Impedance spectroscopy was performed on Sodium Chloride and Magnesium Sulphate solutions to accurately determine Total Dissolved Solids (TDS) in solution. This was done despite the electrical conductivity measurement (the standard technique for determining TDS) of the two types of aqueous solutions being different at similar TDS levels. A novel method for using impedance spectroscopy to differentiate between the two salts in aqueous solution is described. It was found that impedance values from only two frequencies was enough to discriminate between the Sodium Chloride and Magnesium Sulphate solutions, which means that TDS can accurately be determined from the impedance data as the solute is known. Work is in progress to develop a low-cost version of the system to provide point-of-care water quality monitoring solution to those in need.